a) Field of the Invention
The invention is directed to an electronic endoscope with a semiconductor image sensor (CCD chip) for receiving the images received by an objective lens and with an electronic circuit, wherein the endoscope substantially comprises a shaft with a distal and a proximal end, and the objective lens and CCD chip are arranged at the distal end, and the proximal end is held in a housing which holds the shaft and encloses the glass-fiber optical connection.
b) Description of the Related Art
An electronic endoscope of this type is known, for example, from German Patent 39 21 233 and from U.S. Pat. No. 4,253,447 or U.S. Pat. No. 4,261,344.
Such endoscopes, which are used particularly in the field of medicine, must be sterilized after using and in preparation for reuse, especially in their distal area which is introduced into the human body.
In spite of the way in which the previously known endoscopes and CCD chips were constructed and specially arranged inside the endoscope shaft, it is not possible to subject these instruments to autoclaving in their entirety, i.e., they do not withstand for long periods the minimum temperature of 134.degree. C. which is used for this purpose. The reason for this is that the CCD chip unit, which is constructed of a plurality of parts and whose individual structural component parts are glued together and held in a metallic element, becomes "fogged" after several autoclaving processes, namely in that, owing to the temperature increase during autoclaving and the subsequent cooling, the surfaces of the individual parts, especially those of the crystal filter arranged in front of the actual CCD chip and of the IR cutoff filter, deteriorate in quality since the glue applied between their respective adjacent surfaces loses its transparency and becomes opaque.